Abraham Fischer (1850-1913) was the sole Prime Minister of the Orange River Colony in South Africa.

He was originally a lawyer in Cape Colony, joining the bar in 1875. He became vice-president of the Orange Free State's volksraad in 1893 and a member of the executive council in 1896. During the Boer War he went to Europe to solicit support for the Boers, returning in 1903 to practice law in the newly-formed Orange River Colony.

Continuing to promote the Boer cause, he helped form the Oranje Unie party in May 1906 and became its chairman; the party won the majority of seats in the colony's first elections that were held in November 1907. On November 27, he was chosen as Prime Minister, and stayed in that position until it ceased to exist with the union of May 31, 1910. He then joined the cabinet of the Union of South Africa.

He was the grandfather of Bram Fischer, a noted anti-apartheid activist.